Whether gst would be applicable 2 times on a particular item

Yes ... those all rates are inclusive of CGST & SGST.For Example:

Suppose goods worth Rs. 10,000 are sold by manufacturer A in telangana to Dealer B in Telangana. B resells them to trader C in Rajasthan for Rs. 17,500. Trader C finally sells to End User D in Rajasthan for Rs. 30,000.

Suppose CGST= 9%, SGST=9%. Therefore, IGST=9+9=18%

Since A is selling this to B in Telangana itself, it is an intra-state sale and both CGST @ 9% and SGST @ 9% will apply.

B (Telangan) is selling to C (Rajasthan). Since it is an interstate sale, IGST @ 18% will apply.

C (Rajasthan) is selling to D also in Rajasthan. Once again it is an intra-state sale and both CGST @ 9% and SGST @ 9% will apply.